The invention discloses penetrate-layer oil for a cement stabilized macadam base and a preparation method of the penetrate-layer oil. The preparation method involves continuous production processes of modification and emulsification and specifically comprises the steps of adding a modifier for modifying matrix asphalt and then emulsifying to obtain modified emulsified asphalt S; adding a tackifier to the matrix asphalt and carrying out emulsification to obtain modified emulsified asphalt T; and compounding the modified emulsified asphalt S and the modified emulsified asphalt T at the ratio of 1:1 to obtain an environment-friendly high-performance modified emulsified asphalt, namely environment-friendly high-performance penetrate-layer oil. Compared with common emulsified asphalt and kerosene cutback asphalt, the material has the characteristics of good permeability and high caking property, also has good permeability and anti-erosion property, and water damage can be effectively prevented. Meanwhile, the penetrate-layer oil has good adhesive property, and the base and an asphalt pavement have good interlayer bonding, so that the stress state of the asphalt pavement is improved, solvents such as kerosene and the like are not added, the production security is effectively improved and the environmental pollution during construction is reduced.